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Muscle force

Posted: Mon Aug 08, 2022 5:24 am
by amini_opensim
Hello

According to the following muscle force formulation, I would like to get muscle properties.
fff.PNG
fff.PNG (20.66 KiB) Viewed 209 times
where fL is the active-force-length curve, fV is the force-velocity curve, and fPE is the passive-force-length. However, there aren't these properties in LuaMuscle :https://scone.software/doku.php?id=ref:lua_muscle

Is active_fiber_force()*fiber_length() equal to active-force-length?

Would you pls guide me on how to get them?

Thanks

Re: Muscle force

Posted: Mon Aug 08, 2022 5:47 am
by tgeijten
Perhaps you mean muscle:active_force_length_multiplier()?

Re: Muscle force

Posted: Mon Aug 08, 2022 6:16 am
by amini_opensim
I need fL, fV, and fPE.

you mean fl is active_force_length_multiplier().

How about fV and fPE?

Re: Muscle force

Posted: Mon Aug 08, 2022 6:21 am
by tgeijten
Please see the documentation for the available functions:

https://scone.software/doku.php?id=ref:lua_muscle

Re: Muscle force

Posted: Mon Aug 08, 2022 6:27 am
by amini_opensim
I mean the force-velocity and passive-force-length are not available in:
https://scone.software/doku.php?id=ref:lua_muscle

Re: Muscle force

Posted: Mon Aug 08, 2022 6:39 am
by tgeijten
All these curves are available as part of the model, I'm not sure I understand why you would want to compute them in real-time during the simulation.

In any case, if you really need them, you can derive fPE from passive_fiber_force() and fV from the muscle_force() and fiber_velocity().